This invention relates to elongated devices for therapeutic or diagnostic procedures in a wall of a patient's heart, particularly to the treatment of myocardial tissue experiencing ischemic conditions, by revascularization of such myocardial tissue.
Myocardial revascularization typically involves formation of one or more channels in a patient's heart wall which defines the heart chamber, particularly the left ventricle. The first trials of the revascularization process were apparently made by Mirhoseini et al. See for example the discussions in Lasers in General Surgery (Williams & Wilkins; 1989), pp 216-223. Other early disclosures of this procedure are found in an article by Okada et al. in Kobe J. Med. Sci 32, 151-161, October 1986 and in U.S. Pat. No. 4,658,817 (Hardy). Both of these references describe intraoperative revascularization procedures which require the chest wall to be opened and which include formation of the revascularization channels completely through the heart wall, i.e. the epicardium, the myocardium and the endocardium.
Copending application Ser. No. 08/078,443, filed on Jun. 15, 1993 (Aita et al.), which is incorporated herein in its entirety, describes an intravascular system for myocardial revascularization which is introduced percutaneously into a peripheral artery and advanced through the patient's arterial system into the left ventricle of the patient's heart. The revascularization channels are not usually formed through the entire heart wall but only the endocardium and into the myocardium from within the left ventricle. This procedure eliminates the need of the prior intraoperative procedures to open the chest cavity and to penetrate through the entire heart wall in order to form the channel through the endocardium into the myocardium. While the percutaneous method and system for introducing the revascularization device developed by Aita et al. represents a substantial advance, one of the difficulties in forming revascularization channels from within a patient's left ventricle by means of a percutaneously introduced revascularization system has been accurately directing the distal tip of the channel forming device to a desired region of the patient's endocardium and maintaining the placement of the distal end of the channel forming device against a desired region of the ventricular wall at a proper angle, i.e. perpendicular or near perpendicular to the endocardium, while the heart is beating. Maintaining placement of the operative distal tip of the device is important because lateral displacement can affect the channel formation within the heart wall. The anatomy of human hearts and particularly the relationship of the ascending aorta and the left ventricle can vary considerably from patient to patient. The entry angle from the ascending aorta through the aortic valve into the left ventricle of a human heart does not facilitate the easy access to the free wall of the patient's heart which in substantial part defines the left ventricle. Direct entry from the ascending aorta through the aortic valve usually leads into the cordae tendonae of the mitril valve and to the posterior sulcus adjacent to the inferolateral papillary muscle to which the cordae are attached. As a result, the distal extremity of a guiding catheter advanced into the left ventricle through the aortic valve from the ascending aorta can inadvertently become entrapped or entangled with the cordae tendonae or be positioned in the posterior sulcus adjacent to the base of the inferolateral papillary muscle.
What has been needed is an improved delivery system and method for delivering a channel forming or other ablation device within the patient's heart chamber, particularly via percutaneous introduction into the patient's vasculature, which provides for an easy and accurate placement of the device against a desired region of the endocardium at the desired orientation and the maintenance of the position of the device within the patient's heart chamber while tissue is being ablated and the heart is beating. The present invention satisfies these and other needs.